Hooded seals (Cystophora cristata)

Marine mammals 2013
Typography
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Hooded seals form one stock in the Northwest Atlantic and another in the Northeast Atlantic; although, recent genetic studies suggest no biological distinction between the groups (Coltman et al., 2007). In the Northeast Atlantic, whelping takes place in mid-late March in the West Ice, not far from where the West-Ice harp seals give birth. Between breeding and the moult, hooded seals carry out feeding excursions to the continental shelf edge off the Faroe Islands and Northern Ireland and to areas in the Norwegian Sea. 

During moult in June-July, the West Ice stock hauls out on pack-ice north of Jan Mayen. According to satellite-tracking data, seals from this stock occupy ice-covered waters off the east coast of Greenland much of the summer. They also make excursions to the Faroe Islands, the Irminger Sea, north/northeast of Iceland, the Norwegian Sea, along the continental shelf edge from Norway to Svalbard, and into the Barents Sea, presumably to feed in areas of high productivity caused by the upwelling at the shelf and ice edges (Folkow et al., 1996; Kovacs et al., 2011b). During summer excursions, which can last for more than 3 months, the seals apparently never haul out, not even in coastal areas. But, they are seen on land-fast ice and on floes in the Svalbard region from early spring to late autumn (Kovacs and Lydersen, 2006). The number of hooded seals occupying the Svalbard area and entering the Barents Sea is likely to vary from year to year, depending on ice conditions. Hooded seals of the West-Ice stock have been commercially exploited since the mid 1800s and are managed jointly by Norway and Russia. Back-calculation using a population model indicate a possible stock size of 700,000 animals in the West Ice shortly after WWII, while stock size was estimated to be ~82,000 animals in 2007 (ICES WGHARP, 2008). Because of significant declines, this species is now on the Norwegian Red List and the quota has been set to zero since 2007 (ICES WGHARP, 2014).

Similar to other ice-dependent marine mammals of the Barents Sea region, harp and hooded seals are expected to decline with reductions of sea ice in the coming decades (e.g. Kovacs and Lydersen, 2008; Kovacs et al., 2011a, 2012). It has been suggested that reduced body condition of Barents Sea harp seals, observed since 2004, may be partly due to increased distance between breeding areas in the White Sea and summer feeding areas at the ice edge in the Barents Sea (Bogstad et al., 2015). Increased resource competition with a record-large cod stock in the Barents Sea may also be a factor. Although harp seal pup production in the West Ice has not declined, a marked increase in mean age at maturity from the early 1990s to 2009 suggests that these seals are also experiencing reduced habitat quality. The registered declines in West Ice hooded seals and White Sea harp seals — along with harp seal condition declines in summer in the northern Barents Sea — are believed due, in part, to changes in ice distribution and other ecosystems shifts related to climate warming (Bogstad et al., 2015; Kovacs et al., 2011a, 2012).